Why is my dogs head shaking?

This may be due to the likelihood of an ear infection. A vet can prescribe the medication your dog needs to resolve this. This link has a lot more info., including other symptoms you may observe. http://pets.webmd.com/dogs/dog-ear-in...

There are other possibilities (inc. foreign object, infection, allergies, parasite, polyp, tumor, trauma, etc.) detailed in the link below. http://www.md-health.com/Dog-Shaking-...

She may just be very nervous and have high anxiety. Dogs shaking their ears is different from just trembling. If the trembling continues and you are very concerned check with your veterinarian and get his/her opinion.

After working at a veterinary hospital, the most common cause of head shaking are ear mites. You could tell by looking at your dog's inner ear and finding reddish brownish crust. Most forms of ear mites are bacterial, so be sure to ask your veterinarian for a gel or liquid ear mite solution. They can come in the form of drops, gel, or cream. You can also clean your dog's ears to prevent any further infections or buildup.